The explosive growth of the Internet has transformed the way people communicate with each other and conduct business. The Internet is an international network of interconnected computers which provide the means to communicate easily with others and to access easily vast amounts of information from around the world. One aspect of the Internet is the World Wide Web (WWW), which is an amalgamation of on-line web sites that replicate electronically some of the educational, entertainment and commercial offerings of the off-line everyday world.
Typically, personal computer access to the Internet is provided by an Internet Service Provider (ISP), which is able to offer its customers various “on-line” services, including electronic mail, file transfers, and the ability to browse and publish on the WWW. ISPs enable their customers to quickly and efficiently partake of the diverse on-line content and services offered at web sites by combining computer processing, information storage, protocol conversion and routing with communication links to Internet web sites.
To access the Internet, a user dials a directory number to access an ISP facility via a modem through application software resident on the user's computer. Once a connection is established between the user's computer and the ISP facility, the user interacts with the application interface and communicates with the ISP. The ISP acts as a conduit through which the user accesses the offerings of the Internet.
With the increasing popularity of the Internet and the WWW, users are routinely accessing/downloading vast quantities of data as well as exchanging messages and files. This has resulted in a substantial increase in the number of calls placed to ISPs as well as the duration of a typical ISP call. While providing great benefits for users, the increased and extended Internet usage has caused several unexpected problems for the existing Public Switched Telephone Network (PSTN).
In conventional systems, calls from a user to an ISP are handled in the same manner as voice calls. That is, when a call is initiated, signaling—including off-hook signals and touch-tones—is conveyed from the calling phone to telephony equipment located at his/her End Office (An EO, also known as a Class 5 Office, implies that a Class 5 switch is there located to provide local features such as CENTREX, ISDN, etc. Such telephony equipment at an EO is hereinafter referred to as an EO). In the call scenario where the user and the ISP are both served by the same EO, no tandem switching is involved and the call connection is made through activity internal to the EO. In the call scenario where the ISP “point of presence” (PoP) is located in the same local access area as the user, the EO transmits messages to telephony equipment at a Central Office (CO) of a Local Exchange Carrier (such telephony equipment hereinafter referred to as a LEC) which provides local service and switching for both the caller and the ISP. The LEC utilizes a Tandem switching office (Tandem) to connect the EO serving the user to the EO serving the ISP. In the call scenario where the calling party and the ISP are not in the same local service area, the caller's EO transmits messages to its LEC Tandem which provides the caller's local service and switching. The calling party's Tandem establishes a connection to the ISP through a corresponding EO of the LEC serving the ISP. Communication between equipment serving the calling party and called party may be across competitive long distance carrier (IXC) networks through an IXC PoP serving LECs at each end.
In cases involving tandem switching, the call originating Tandem selects an idle trunk between itself and the call destination location. Described herein is a direct connection from a call originating Tandem to call destination Tandem. However, it should be understood that signaling may be routed through multiple intermediary locations in the PSTN in order to reach the call destination Tandem. The call originating Tandem formulates an initial address message (IAM) and transmits the message across the PSTN to the call destination Tandem. Upon the destination Tandem's receipt of the IAM, determination that it serves the called number, and determination that the called number is currently idle, the destination Tandem formulates an address complete message (ACM) which is routed back to the call originating Tandem. At the same time, the destination Tandem completes the call path in the backwards direction. When and/or if the called subscriber picks up the phone, the destination Tandem formulates an answer message (ANM). By this time, the trunk must also be connected to the called line in both directions to allow conversation. The call originating Tandem ensures that the calling subscriber is connected to the outgoing trunk (in both directions) so that the parties are able to communicate with each other, exchanging voice or Internet Protocol (IP) data, depending on the type of communication initiated. When either party first hangs up, the corresponding equipment generates a release message (REL) addressed to the other party's equipment, which identifies the trunk associated with the call that is to be disconnected and returned to idle status. Once idled on one end, a release complete message (RLC) is generated and addressed back to the sender of the REL to idle the identified trunk.
As described, in conventional systems, the circuit switches and transmission line allocated for the call remain allocated for a particular call until released at the call's conclusion. Due to the extended duration of typical calls to an ISP, the PSTN's embedded base of circuit switches experience higher usage rates, causing considerable congestion at times when the network is carrying a significant number of calls supporting IP dial-up traffic. This burden on the existing circuit switch backbone of the PSTN is expected to become worse as the projected number of Internet users reaches and exceeds 100 million over the next few years. With the increased usage of PSTN facilities attributable to Internet traffic, the switching and transmission facilities of the PSTN will rapidly approach capacity.
To avoid unacceptable service degradation due to network facilities operating at or near capacity, the standard method for increasing network capacity is to build out the circuit switches of the network at each LEC, as well as to increase inter-switch transmission capacity. However, this solution is costly in both monetary and spatial requirements. Furthermore, PSTN service providers plan in the future to migrate from the existing bandwidth limited switched circuit networks to packet oriented networks which support the transport of voice, data, and video services. Thus, building out the circuit switching network to address Internet-driven traffic congestion is not only an inefficient and expensive approach, it also fails to consider the future evolution of the PSTN.